Under what conditions is a departure allowed to take off in relation to an arriving aircraft when there is an absence of an appropriate fix?

In air traffic control, when managing departures in relation to arriving aircraft, it is essential to maintain safe separation to prevent any potential conflicts. The guidance for this scenario indicates that a departure can be cleared to take off under specific conditions, particularly in the absence of an appropriate fix to determine spacing.

The correct choice indicates that a departure may be allowed to take off three minutes prior to the arrival of an aircraft. This time frame has been established based on practical operational experience and safety considerations, ensuring that the departure has adequate time to climb and maintain a safe distance from the arriving aircraft as both maneuvers occur.

This procedure helps mitigate the risks associated with closely timed departures and arrivals, as it allows the departing aircraft to gain altitude and distance before the arriving aircraft reaches the same location in the airspace. Overall, this three-minute separation provides a buffer that reinforces safety standards.